It has long been known to use heating, ventilation and air conditioning systems (“HVAC”) to provide ventilation to enclosed structures. HVAC usually comprises one or more blowers connected to a circuit of ventilation ducts to control the amount and direction of airflow throughout the structure. While some fresh air will usually be introduced into the system, much of the air within the enclosed structure is recycled through the system. HVAC is also typically employed, as the name suggests, to control the air temperature of the enclosed environment by controlling the temperature of the air directed therein.
The introduction of cool air into an HVAC system will often lower the temperature of the warmer air within the ventilation ducts forcing the warmer air to release portions of the humidity therein. Similarly, when cool air has cooled the temperature of the ventilation ducts and warmer air is then introduced into the ventilation ducts, humidity from the warmer air may condense onto the cool ventilation ducts. Also, the humidity from warm air passing over a chiller used to cool the air circulating through the HVAC will likewise condense on the chiller. In any case, HVAC systems are prone to having moisture therein.
The dark and damp conditions within the ducts of an HVAC system are conducive to the rapid growth and reproduction of contaminants such as molds, spores, bacteria, viruses and mildews which may be harmful to the people for whom the air traveling therethrough is intended. HVAC systems thus become a breeding ground for these contaminants. Inhabitants may suffer adverse physical reactions as a result, especially if they are allergic to any of the contaminants. This problem is exacerbated when the inhabitants themselves introduce additional contaminants into the HVAC system that may then multiply in the contaminant friendly HVAC environment and spread to other inhabitants located within the structure. Air filters have been introduced into HVAC systems in an attempt to remove contaminants passing therethrough before they reach inhabitants. However, these filters often become damp themselves and provide conditions which foster growth and reproduction of the contaminants.
It is known that light of the “C” band of the ultraviolet spectrum, with wavelengths between approximately 220 and 288 nanometers, (“UV light”) can control growth of or kill most contaminants currently known to exist within HVAC systems. The longer the period of time a unit of air is exposed to UV light, and the greater the density of the UV light that a unit of air is exposed to, the greater the number of contaminants within the unit of light will be killed thereby. Lamps capable of emitting UV light typically comprise a long, hollow cylinder containing one or more gasses therein that will, upon being excited by electric current, emit UV light. These UV lamps primarily radiate UV light in a direction perpendicular to the surface from which the light emanates. Therefore, UV light emits radially from tubular lamps. In other words, UV light is only emitted in directions perpendicular to the length of the UV light tube. Additionally, the intensity of the UV light emitted at any point measured radially from the lamp is inversely related to the radial distance as measured from the tubular UV light source.
The intensity of UV light emitted from UV lamps is commonly measured in microWatts. Longer UV lamps generally emit a greater intensity of UV light than shorter lamps. For example, a twelve inch UV lamp may produce 37 microWatts at one meter from the lamp, an eighteen inch UV lamp may produce 73 microWatts at one meter from the lamp, and a twenty-eight inch UV lamp may produce 133 microWatts at one meter from the lamp. Therefore, in order to increase the intensity of UV light within an air duct and maximize the effectiveness of the UV device, it is desirable to employ the longest lamp that will fit within a given duct size.
Known configurations of UV lamps in HVAC systems fail to provide a sufficient amount of UV light to control growth of or kill the desired amount of contaminants. Accordingly it would be desirable to employ a device that can increase the effectiveness of a tubular UV lamp used to control or kill contaminants within an HVAC system.